1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
18 #include <Riostream.h>
20 #include "AliITSsegmentationSSD.h"
22 //////////////////////////////////////////////////////
23 // Segmentation class for //
26 //////////////////////////////////////////////////////
27 const Float_t AliITSsegmentationSSD::fgkDxDefault = 72960.;
28 const Float_t AliITSsegmentationSSD::fgkDzDefault = 40000.;
29 const Float_t AliITSsegmentationSSD::fgkDyDefault = 300.;
30 const Float_t AliITSsegmentationSSD::fgkPitchDefault = 95.;
31 const Int_t AliITSsegmentationSSD::fgkNstripsDefault = 768;
33 ClassImp(AliITSsegmentationSSD)
34 AliITSsegmentationSSD::AliITSsegmentationSSD(): AliITSsegmentation(),
44 // default constructor
46 //----------------------------------------------------------------------
47 AliITSsegmentationSSD::AliITSsegmentationSSD(AliITSgeom *geom):
60 SetDetSize(fgkDxDefault,fgkDzDefault,fgkDyDefault);
61 SetPadSize(fgkPitchDefault,0.);
62 SetNPads(fgkNstripsDefault,0);
67 //______________________________________________________________________
68 void AliITSsegmentationSSD::Copy(TObject &obj) const {
69 // protected method. copy this to obj
70 AliITSsegmentation::Copy(obj);
71 ((AliITSsegmentationSSD& ) obj).Clear();
72 ((AliITSsegmentationSSD& ) obj).fNstrips = fNstrips;
73 ((AliITSsegmentationSSD& ) obj).fStereoP = fStereoP;
74 ((AliITSsegmentationSSD& ) obj).fStereoN = fStereoN;
75 ((AliITSsegmentationSSD& ) obj).fStereoPl5 = fStereoPl5;
76 ((AliITSsegmentationSSD& ) obj).fStereoNl5 = fStereoNl5;
77 ((AliITSsegmentationSSD& ) obj).fStereoPl6 = fStereoPl6;
78 ((AliITSsegmentationSSD& ) obj).fStereoNl6 = fStereoNl6;
79 ((AliITSsegmentationSSD& ) obj).fLayer = fLayer;
80 ((AliITSsegmentationSSD& ) obj).fPitch = fPitch;
81 ((AliITSsegmentationSSD& ) obj).fLayer = fLayer;
85 //______________________________________________________________________
86 AliITSsegmentationSSD& AliITSsegmentationSSD::operator=(
87 const AliITSsegmentationSSD &source){
94 //______________________________________________________________________
95 AliITSsegmentationSSD::AliITSsegmentationSSD(const AliITSsegmentationSSD &source):
96 AliITSsegmentation(source),
109 //----------------------------------------------------------------------
110 void AliITSsegmentationSSD::Init(){
111 // standard initalizer
113 SetPadSize(fgkPitchDefault,0.);
114 SetNPads(fgkNstripsDefault,0);
117 //----------------------------------------------------------------------
118 void AliITSsegmentationSSD::Angles(Float_t &aP,Float_t &aN) const{
119 // P and N side stereo angles
129 //----------------------------------------------------------------------
130 void AliITSsegmentationSSD::SetLayer(Int_t l){
131 //set fLayer data member (only 5 or 6 are allowed)
134 if((l!=5) && (l!=6))Error("SetLayer","Layer can be 5 or 6, not %d",l);
136 //----------------------------------------------------------------------
137 void AliITSsegmentationSSD::GetPadTxz(Float_t &x,Float_t &z) const{
138 // returns P and N sided strip numbers for a given location.
139 // Transformation from microns detector center local coordinates
140 // to detector P and N side strip numbers..
143 fNstrips v | N-Side ...0
144 \-------/------------|-----------\--------\
145 |\\\\\\/////////////.|\\\\\\\\\\\\\\\\\\\\|
146 |0\\\\/////////////..|.\\\\\\\\\\\\\\\\\\\|
147 |00\\/////////////...|..\\\\\\\\\\\\\\\\\\|
148 X <--|000/////////////... |...\\\\\\\\\\\\\\\\\|
149 |00/////////////... | ...\\\\\\\\\\\\\\\\|
150 |0/////////////... | ...\\\\\\\\\\\\\\\|
151 |//////////////... | ...\\\\\\\\\\\\\\\|
152 /-----\--------------|--------------------/
153 fNstrips-1 P-Side ...0
159 // expects x, z in microns
161 Float_t stereoP, stereoN;
162 Angles(stereoP,stereoN);
163 Float_t tanP = TMath::Tan(stereoP);
164 Float_t tanN = TMath::Tan(-stereoN);
169 x = (x1 - z1*tanP)/fPitch;
170 z = (x1 - tanN*(z1 - fDz))/fPitch;
172 //----------------------------------------------------------------------
173 void AliITSsegmentationSSD::GetPadIxz(Float_t x,Float_t z,Int_t &iP,Int_t &iN) const {
174 // returns P and N sided strip numbers for a given location.
177 fNstrips v | N-Side ...0
178 \-------/------------|-----------\--------\
179 |\\\\\\/////////////.|\\\\\\\\\\\\\\\\\\\\|
180 |0\\\\/////////////..|.\\\\\\\\\\\\\\\\\\\|
181 |00\\/////////////...|..\\\\\\\\\\\\\\\\\\|
182 X <--|000/////////////... |...\\\\\\\\\\\\\\\\\|
183 |00/////////////... | ...\\\\\\\\\\\\\\\\|
184 |0/////////////... | ...\\\\\\\\\\\\\\\|
185 |//////////////... | ...\\\\\\\\\\\\\\\|
186 /-----\--------------|--------------------/
187 fNstrips-1 P-Side ...0
194 // expects x, z in microns
197 Float_t stereoP, stereoN;
198 Angles(stereoP,stereoN);
199 Float_t tanP=TMath::Tan(stereoP);
200 Float_t tanN=TMath::Tan(stereoN);
204 Float_t ldX = x1 - z1*tanP; // distance from left-down edge
205 iP = (Int_t)(ldX/fPitch);
207 iP = (iP>fNstrips)? -1: iP;
209 ldX = x1 - tanN*(fDz - z1);
210 iN = (Int_t)(ldX/fPitch);
212 iN = (iN>fNstrips)? -1: iN;
215 //-------------------------------------------------------
216 void AliITSsegmentationSSD::GetPadCxz(Int_t iP,Int_t iN,Float_t &x,Float_t &z) const {
217 // actually this is the GetCrossing(Float_t &,Float_t &)
218 // returns local x, z in microns !
220 Float_t lDx = fDx; // detector size in x direction, microns
221 Float_t lDz = fDz; // detector size in z direction, microns
222 Float_t xP; // x coordinate in the P side from the first P strip
223 Float_t xN; // x coordinate in the N side from the first N strip
224 Float_t stereoP, stereoN;
225 Angles(stereoP,stereoN);
226 Float_t kP=TMath::Tan(stereoP);
227 Float_t kN=TMath::Tan(stereoN);
231 x = xP + kP*(lDz*kN-xP+xN)/(kP+kN);
232 z = (lDz*kN-xP+xN)/(kP+kN);
235 //if(TMath::Abs(z) > Dz/2) cout<<"Warning, wrong z local ="<<z<<endl;
236 // Check that zL is inside the detector for the
237 // correspondent xP and xN coordinates
241 //______________________________________________________________________
242 Bool_t AliITSsegmentationSSD::LocalToDet(Float_t x,Float_t z,
243 Int_t &iP,Int_t &iN) const {
244 // Transformation from Geant cm detector center local coordinates
245 // to detector P and N side strip numbers..
248 fNstrips v | N-Side ...0
249 \-------/------------|-----------\--------\
250 |\\\\\\/////////////.|\\\\\\\\\\\\\\\\\\\\|
251 |0\\\\/////////////..|.\\\\\\\\\\\\\\\\\\\|
252 |00\\/////////////...|..\\\\\\\\\\\\\\\\\\|
253 X <--|000/////////////... |...\\\\\\\\\\\\\\\\\|
254 |00/////////////... | ...\\\\\\\\\\\\\\\\|
255 |0/////////////... | ...\\\\\\\\\\\\\\\|
256 |//////////////... | ...\\\\\\\\\\\\\\\|
257 /-----\--------------|--------------------/
258 fNstrips-1 P-Side ...0
265 const Double_t kconst = 1.0E-04; // convert microns to cm.
267 x /= kconst; // convert to microns
268 z /= kconst; // convert to microns
269 this->GetPadTxz(x,z);
273 if(iP<0 || iP>=fNstrips) iP=-1; // strip number must be in range.
276 if(iN<0 || iN>=fNstrips) iN=-1; // strip number must be in range.
279 //----------------------------------------------------------------------
280 void AliITSsegmentationSSD::DetToLocal(Int_t ix,Int_t iPN,
281 Float_t &x,Float_t &z) const{
282 // Transformation from detector segmentation/cell coordiantes starting
283 // from 0. iPN=0 for P side and 1 for N side strip. Returned is z=0.0
284 // and the corresponding x value..
287 fNstrips v | N-Side ...0
288 \-------/------------|-----------\--------\
289 |\\\\\\/////////////.|\\\\\\\\\\\\\\\\\\\\|
290 |0\\\\/////////////..|.\\\\\\\\\\\\\\\\\\\|
291 |00\\/////////////...|..\\\\\\\\\\\\\\\\\\|
292 X <--|000/////////////... |...\\\\\\\\\\\\\\\\\|
293 |00/////////////... | ...\\\\\\\\\\\\\\\\|
294 |0/////////////... | ...\\\\\\\\\\\\\\\|
295 |//////////////... | ...\\\\\\\\\\\\\\\|
296 /-----\--------------|--------------------/
297 fNstrips-1 P-Side ...0
305 // x = a + b + z*tan(fStereoP); a = Dpx(iP)*(iP+0.5)-dx; b = dz*th;
307 // x = a + b + z*tan(fStereoP); a = Dpx(iN)*(iN+0.5)-dx; b = -dz*th;
308 const Double_t kconst = 1.0E-04; // convert microns to cm.
309 Float_t flag=kconst*Dx(); // error value
310 Double_t th=0.0,dx,dz,i,a,b=0.0,xb[4],zb[4];
311 Float_t stereoP, stereoN;
312 Angles(stereoP,stereoN);
314 z = 0.0; // Strip center in z.
315 if(iPN<0 || iPN>1){// if error return full detector size in x.
319 if(ix<0 || ix>=fNstrips) { // if error return full detector size in x.
323 i = (Double_t) ix; // convert to double
324 dx = 0.5*kconst*Dx(); // half distance in x in cm
325 dz = 0.5*kconst*Dz(); // half distance in z in cm
326 a = kconst*Dpx(ix)*(i+0.5)-dx; // Min x value.
327 if(iPN==0){ //P-side angle defined backwards.
328 th = TMath::Tan(stereoP);
330 }else if(iPN==1){ // N-side
331 th = TMath::Tan(-stereoN);
334 // compute average/center position of the strip.
335 xb[0] = +dx; if(th!=0.0) zb[0] = (+dx-a-b)/th; else zb[0] = 0.0;
336 xb[1] = -dx; if(th!=0.0) zb[1] = (-dx-a-b)/th; else zb[1] = 0.0;
337 xb[2] = a+b+dz*th; zb[2] = +dz;
338 xb[3] = a+b-dz*th; zb[3] = -dz;
340 for(Int_t j=0;j<4;j++){
341 if(xb[j]>=-dx && xb[j]<=dx && zb[j]>=-dz && zb[j]<=dz){
350 //----------------------------------------------------------------------
351 Bool_t AliITSsegmentationSSD::GetCrossing(Int_t iP,Int_t iN,
352 Float_t &x,Float_t &z,
354 // Given one P side strip and one N side strip, Returns kTRUE if they
355 // cross each other and the location of the two crossing strips and
356 // their correxlation matrix c[2][2].
359 fNstrips v | N-Side ...0
360 \-------/------------|-----------\--------\
361 |\\\\\\/////////////.|\\\\\\\\\\\\\\\\\\\\|
362 |0\\\\/////////////..|.\\\\\\\\\\\\\\\\\\\|
363 |00\\/////////////...|..\\\\\\\\\\\\\\\\\\|
364 X <--|000/////////////... |...\\\\\\\\\\\\\\\\\|
365 |00/////////////... | ...\\\\\\\\\\\\\\\\|
366 |0/////////////... | ...\\\\\\\\\\\\\\\|
367 |//////////////... | ...\\\\\\\\\\\\\\\|
368 /-----\--------------|--------------------/
369 fNstrips-1 P-Side ...0
375 c[2][2] is defined as follows
376 /c[0][0] c[0][1]\ /delta iP\ = /delta x\
377 \c[1][0] c[1][1]/ \delta iN/ = \delta z/
379 const Double_t kconst = 1.0E-04; // convert microns to cm.
380 Double_t thp,thn,th,dx,dz,p,ip,in;
381 Float_t stereoP, stereoN;
382 Angles(stereoP,stereoN);
384 thp = TMath::Tan(stereoP);
385 thn = TMath::Tan(-stereoN);
387 if(th==0.0) { // parall strips then never cross.
390 c[0][0] = c[1][0] = c[0][1] = c[1][1] = 0.0;
393 // The strips must cross some place in space.
394 ip = (Double_t) iP; // convert to double now for speed
395 in = (Double_t) iN; // convert to double now for speed
396 dx = 0.5*kconst*Dx(); // half distance in x in cm
397 dz = 0.5*kconst*Dz(); // half distance in z in cm
398 p = kconst*Dpx(iP); // Get strip spacing/pitch now
399 x = 0.5*p+dx + (p*(in*thp-ip*thn)-2.0*dz*thp*thn)/th;
400 z =(p*(in-ip)-dz*(thp+thn))/th;
401 // compute correlations.
402 c[0][0] = -thn*p/th; // dx/diP
403 c[1][1] = p/th; // dz/diN
404 c[0][1] = p*thp/th; // dx/diN
405 c[1][0] = -p/th; // dz/diP
406 if(x<-dx || x>dx || z<-dz || z>dz) return kFALSE; // crossing is outside
407 // of the detector so
408 // these strips don't
413 //----------------------------------------------------------------------
414 void AliITSsegmentationSSD::PrintDefaultParameters() const {
415 // Print default values for parameters.
416 // Values specified as static const data members are shown
418 cout<<"fgkDxDefault = "<<fgkDxDefault<<endl;
419 cout<<"fgkDzDefault = "<<fgkDzDefault<<endl;
420 cout<<"fgkDyDefault = "<<fgkDyDefault<<endl;
421 cout<<"fgkPitchDefault = "<<fgkPitchDefault<<endl;
422 cout<<"fgkNstripsDefault = "<<fgkNstripsDefault<<endl;